1. Field of the Invention
The invention relates to a hybrid vehicle that is driven by motive power output from at least one of an internal combustion engine and a vehicle-driving electric motor and a method of controlling the hybrid vehicle, and in particular, to a hybrid vehicle in which an exhaust passage of the internal combustion engine is provided with an electrically-heated catalyzer and an on-board electricity storage device can be charged by an external power source outside of the vehicle and a method of controlling the hybrid vehicle.
2. Description of the Related Art
Japanese Patent Application Publication No. 2005-83243 (JP-A-2005-83243) discloses a device for increasing temperature of car exhaust gas. The exhaust gas temperature increasing device is provided between an internal combustion engine and a DPF device provided in an exhaust gas passage and increases the temperature of exhaust gas introduced from the internal combustion engine into the DPF device. In the exhaust gas temperature-increasing device, for example, after driving a vehicle, the temperature of exhaust gas is increased by electric power received from an external power source outside of the vehicle in a state where the vehicle is parked in a garage or a parking lot and the internal combustion engine is idled. In this way, it is possible to burn off the particulate material accumulated on a catalytic filter during driving (see JP-A-2005-83243).
In recent years, hybrid vehicles, which are driven by motive power output from at least one of an engine and a vehicle-driving electric motor, have attract public attention. A hybrid vehicle is equipped with an electricity storage device, an inverter, and a motor that is driven by the inverter as a driving power source, in addition to the conventional engine.
As such a hybrid vehicle, a vehicle is already available in which the electricity storage device mounted on the vehicle can be charged by an external power source. For example, the electricity storage device is charged by a domestic power source by connecting, through a charging cable, a charging port provided in the vehicle and a power socket provided in a house. Such a hybrid vehicle, in which the on-board electricity storage device can be charged by such an external power source is hereinafter also referred to as the “plug-in hybrid vehicle.”
The plug-in hybrid vehicle is also equipped with an engine, and therefore, a catalyzer for purifying exhaust gas is needed. Because the plug-in hybrid vehicle can receive electric power from an external power source, an electrically-heated catalyzer (EHC) is provided in the exhaust gas passage and it is possible to supply electricity from the external power source to the EHC during charging of the electricity storage device by the external power source in preparation for start of the engine after the vehicle starts running.
However, when an electrical abnormality occurs in the EHC, there is a possibility that when the electricity storage device is charged by the external power source, an overcurrent flows from the external power source to the EHC, which can badly affect on the external power source. In the above-cited JP-A-2005-83243, there is no discussion concerning such a problem.